Adopted in positioning during aluminum alloy wheel machining is a cast process lip, and the cast blank deforms in the cooling process and after thermal treatment, so that the axial positioning surface and radial positioning surface of the cast process lip are raised and sunken. When the axial positioning surface and radial positioning surface of the cast process lip deform greatly, the machined and clamped wheel skews, and the machined product has the defects of skewing, machining failure of inner and outer rims and the like.